There has been known an angle measuring device for measuring an angle formed between a measured line and a vertical line. For example, in the field of rehabilitation, the angle measuring device described in Japanese Patent No. 4445468, for example, is used when measuring angles at various positions of a body. Such an angle measuring device includes: a first arm; a second arm; a support member attached to one end of the second arm; angular scale marks indicating opening angles of the first and second arms; and an inclination angle meter that detects an orientation of the support member with respect to the vertical line.